1. Field of the Invention
The present invention relates to a muffler for muffling low-frequency sound waves.
2. Discussion of Background
For numerous fluid-flow engines, or components of fluid-flow engines (combustion chambers, control valves, etc.), the impedance properties of flow feed lines, especially with regard to low-frequency natural acoustic vibrations of such components, play an important role in relation to their acoustic stability properties. Sound waves, which are radiated into feed lines, ought not to be reflected, or to be reflected at most to a slight extent. Otherwise, the reflected waves can contribute to the excitation of strong resonant vibrations. As a rule, the effective muffling of high-frequency sound waves can be achieved with simple technical arrangements (e.g. employment of a classical muffler: perforated sheet above a small closed cavity). By contrast, the muffling of low-frequency sound waves is disproportionally more difficult. A current technique consists in coupling large Helmholz resonators to the feed lines. However, the disadvantage of such a measure consists in that such muffling resonators take up a lot of space and are correspondingly elaborate and expensive. Moreover, the frequency bandwidth of the muffling is very small, and the muffling effect is weak, even in the optimum frequency band.